To date, no effective vaccine against HIV is commercially available. Different HIV clades predominate in certain regions of the world. For example, clade C is found predominantly in India, clade E in south east Asia, and clade B in North America. There is a need to develop vaccine that can be formulated either as broadly reactive against a variety of clades, or which is specifically tailored to a regional clade.
Infection of humans with HIV-1 results in immunity that while rarely protective, nonetheless creates strong negative pressure on viral replication in vivo manifested as antigenic variation. Indeed, a recent study has demonstrated that cellular immunity is directed against variable epitopes much more frequently than previously appreciated (Altfeld, M., et al., J Virol (2003), 77(13), 7330-7340).
A process for preparation of an immunogenic peptide mixture is described by Torres in co-owned U.S. patent application Ser. No. 10/072,084 (publication number 2002/0183484), herein incorporated by reference. According to this process, immunogenic eptitope sequences of a pathogen are assessed, and variability is evaluated. A peptide mixture is synthesized comprising different peptides representative of the frequency with which different amino acids are found at variable residues of selected epitopes of pathogenic proteins. Although this document teaches the specific method by which a peptide mixture can be formulated, there is still a need to formulate specific anti-HIV vaccine compositions.